diff --git a/src/sparsemap.c b/src/sparsemap.c
index 8c4530d..552de55 100644
--- a/src/sparsemap.c
+++ b/src/sparsemap.c
@@ -1282,15 +1282,12 @@ sparsemap_merge(sparsemap_t *map, sparsemap_t *other)
       __sm_chunk_t src_chunk;
       __sm_chunk_map_init(&src_chunk, src + sizeof(sm_idx_t));
       size_t src_size = __sm_chunk_map_get_size(&src_chunk);
-      uint8_t buf[sizeof(sm_idx_t) + sizeof(sm_bitvec_t) * 2] = { 0 };
       if (dst_count == 0) {
-        __sm_append_data(map, &buf[0], sizeof(buf));
+        __sm_append_data(map, src, sizeof(sm_idx_t) + src_size);
       } else {
         size_t offset = __sm_get_chunk_map_offset(map, dst_start);
-        __sm_insert_data(map, offset, &buf[0], sizeof(buf));
+        __sm_insert_data(map, offset, src, sizeof(sm_idx_t) + src_size);
       }
-      memcpy(dst + sizeof(sm_idx_t), &src_chunk, src_size);
-      *(sm_idx_t *)dst = src_start;
 
       /* Update the chunk count and data_used. */
       __sm_set_chunk_map_count(map, __sm_get_chunk_map_count(map) + 1);